Fluid streams, particularly air and gas streams, often carry particulate material therein. The removal of some or all of the particulate material from the fluid stream is needed. For example, air intake streams to the cabins of motorized vehicles, air in computer disk drives, HVAC air, clean room ventilation air, air to engines for vehicles or power generation equipment, gas streams directed to gas turbines, and air streams to various combustion furnaces, often include particulate material therein. In the case of cabin air filters it is desirable to remove the particulate matter for comfort of the passengers and/or for aesthetics. With respect to air and gas intake streams to engines, gas turbines and combustion furnaces, it is desirable to remove the particulate material because particulate can cause substantial damage to the internal workings of the various mechanisms involved. In other instances, production gases or off-gases from industrial processes or engines may contain particulate material therein. Before such gases are discharged to the atmosphere, it is typically desirable to obtain a substantial removal of particulate material from those streams.
Higher and higher efficiency filters are needed to get cleaner air or gas streams. Low pressure is desired to have less restriction to air flow caused by high efficiency filters. Also, longer life is desired to reduce the maintenance and filter costs, which is often a challenge in high efficiency filters. Thus, there continues to be a need for high performance filters, i.e., high efficiency, low pressure-drop, long-life filters.
In certain environments where air filtration is required in highly humid environments, such as off-shore and coastal environments, conventional filter media are unsuitable. For example, such filter media may not be watertight. Thus, there continues to be a need for new filter media in such applications.
Furthermore, although the filter media and filters of the present disclosure may be used in a variety of applications, they are particularly suitable for use with gas turbine filter systems. Gas turbine systems are useful in generating electricity, and they utilize air for combustion purposes. Due to the precision moving parts in these types of systems, the combustion air needs to be clean. To ensure clean air for combustion, air filters have been used to clean the air taken into the gas turbine system. New requirements from the Power Generation industry require even cleaner air entering the turbine blades than previously required. Conventional filter media do not have sufficient performance characteristics (e.g., sufficiently high efficiency filtration while maintaining a low pressure drop) to prevent compressor blade fouling, which reduces the overall efficiency of the turbine.